TiO2 Scattering Optimization and Not-In-Kind Opacity Alternatives

By Michael Diebold, Robert Kwoka, David Mukoda

With titanium dioxide (TiO₂) in short supply, many coatings manufacturers are re-evaluating their paint formulas to optimize TiO₂ effectiveness and/or incorporate not-in-kind alternative options for opacity. Applying optical theory to practical paint making leads us to the following conclusions, which will be explored more thoroughly in this article:

1. Incorporating air voids into a coating, either by formulating above critical pigment volume concentration or by using hollow sphere opaque polymers, can provide good dry film optical performance at reduced TiO₂ loadings, but the use of air voids is constrained by other coating performance parameters.
2. Replacing large extender particles with small extender particles can improve TiO₂ light scattering efficiency, allowing some reduction in TiO₂ loadings, but this is not likely a result of the smaller extenders preferentially “spacing” the TiO₂ particles.
3. Targeted spacing technologies, like the use of highly coated TiO₂ products, can improve TiO₂ efficiency, allowing a reduction in TiO₂ pigment loading in appropriate coating formulations.